sam1, I think you have the right idea. . . take a few physics courses. There's a lot of confusion here. I was going to stay out of it, but I can only resist for so long.
So far, Installshield 2 and dimitrik4 are on the right track.
Installshield 2 lost a few pionts with me from this statement "why the english system uses lbs as A) weight, B)force and for the utterly confused C) mass is ridiculous..." (scratch) SAE or metric, weight is the product of gravitational acceleration acting on mass. So that just narrows it down to two 1) pounds force (lbf) or 2) pounds mass (lbm). Still can be confusing, but there's still a correlation --> gravity.
Same with dimitrik4 with "torque = lb-m*ft = ft*lb-m = lb-ft". In the SAE system, we rarely work with pounds mass (lbm). Oftentimes, we are referring to pounds force (lbf).
Installshield 2 and dimitrik4 both identified that torque and work are different. In order for work and torque to relate, you need translation. For example, take one point on the outside of a tire. Lift the vehicle and spin the tire one complete revolution. The spot is in the same place. No work was done. (bike) Now, lower the vehicle, start it, put it in gear and allow the vehicle to move so that the tire rotates one complete revolution. Now the same spot has moved the same distance forward as the circumferance of the tire, provided you didn't peel out. Alas, work was performed. A force was applied (torque translated via a moment arm) and the point is in a different spot, so we now have displacement. So how do you find the circumferance of the tire? Hmmm, I seem to remember the circumferance of a circle was 2πr. Well, π is a constant frequently abreviated down to 3.14. So we can simplify and say 6.28r. 6.28 sound familiar? Gen1GT mentioned it earlier. 6.28 = 2π = 1 revolution. Unfortunately, shortly after he posted this: So if 1hp is equal to 33,000ft/lbs per minute, how do you explain the formula of hp=torque*RPM/5252? If we use ft/lbs in that formula, it would be off by a factor of 6.28. Fact is, the British system IS retarded, and there IS a difference between ft-lbs and lb-ft. 1 lb-ft is equal to 6.28ft-lbs. Which is how 33,000 is factored down to 5252.
In this situation, all the units cancelled out except for the R in RPM. The R stands is for revolutions, which is why the factor of 6.28 is needed.
EDIT:
I got a little side-tracked by the physics discussion. I wanted to add to the original discussion on torque and horsepower. Think of pushing something to make it spin, like the pedals on a single speed bicycle. Remember how much it sucked because the bigger kids had 10-speeds or better and they were able to go much faster? That's were torque is used.
Pretend you're at a standstill. In order to get started, you have to push fairly hard. That's a high amount of torque, but low speed, so low HP. Now your up to speed and cruising - little effort, low torque, low HP. Now you want to speed up so you pedal faster, high torque, high HP. Now you are going as fast as you can on your little single speed, you can't speed up anymore because your feet can't push hard while going that fast. Guess what? Since you couldn't push hard, you couldn't apply anymore torque and you weren't able to accelerate anymore. You reached the end of your torque curve. Now if you had more POWER, you would've been able to push hard even though you were going that fast. See how HP can benefit?
Next thing you know, you've turned 12 and your folks bought you a 10-speed. You can go fast without having to pedal your heart out. You've just used gearing to take advantage of your powerband. Congratulations and happy birthday!!!
So HP is not quite how fast you can make torque, more like, the ablility to deliver torque while going that fast. Because if the torque you're providing translates to a force greater than the forces acting against you (friction or drag) you can accelerate. Once the forces equal, you can no longer accerlerate. If you can't accelerate, you can't make HP.
Thank you for your time. Keep up the good work.(naughty)
